1. Field of the Invention
The field generally relates to making a passageway through or around an occlusion in a blood vessel, generally an artery. There are several types of prior art for creating a passageway by: 1 expanding a balloon in the center of an occlusion thus pushing it aside, 2 removing the occlusion through a process of grinding, scraping, freezing, lasering or other means, 3 placement of a bypass passageway adventitial to artery wall, or 4 placement of a false lumen between layers of artery wall to bypass occlusion and inflating balloons in false lumen to push inner layer of artery wall and occlusion to side of true lumen. Only the last named is the object of the present invention.
2. Prior Art
Prior Art References
U.S. Patent/Application NumberYearName5,458,6391995 OctoberTsukashima et al.6,500,1472002 DecemberOmaleki et al.6,511,4582003 JanuaryMilo et al.6,551,3142003 AprilHill et al.6,554,7952003 AprilBagaoisan et al.6,682,5422004 JanuaryHarkrider6,736,8272004 MayMcAndrew et al.7,169,1602007 JanuaryMiddleman et al.2004/01675542004Simpson et al.7,179,2702007 Feb. 20Mackower2007/02655962007 Nov. 15Jen et al.2008/02430652008 Oct. 02Rottenberg et al.2008/01541722008 Jun. 26Mauch7,713,2152010 May 11Shriver7,771,4222010 Aug. 10Shriver8,241,3112012 Aug. 14Ward et al.
3. Objects and Advantages
There is a subintimal (SI) technique for twisting a J-tip guidewire in a tapered catheter through a puncture site at the proximal cap of an occlusion in the true lumen of an artery and deliberately dissecting a false lumen between intimal and medial layers of the artery wall with the loop formed by the J-tip guidewire to bypasses the occlusion from its proximal cap to its distal cap. The J-tip guidewire pierces the intimal flap to re-enter the true lumen in a percentage of cases but prior art devices are used to find the direction in which the true lumen lies from the false lumen by ultrasound or orthogonal X-ray fluoroscopy in an additional 10-15% of cases. These prior art devices are marketed as Pioneer® and Outback®. While being successful with a percentage of cases, they are ineffective in an additional percentage of cases which varies but is 20% in some centers where they are used. Additionally, because they are of relatively large diameter they are limited to use in relatively large vessels, such femoral arteries and some popliteal arteries but are too large to be used in coronary arteries or in smaller vessels below-the-knee. These prior art devices use a hollow needle around the J-tip guidewire to pierce the intimal layer at an acute angle which dangerously points toward artery wall opposite. With prior art devices, after the true lumen is re-entered, a balloon is inflated repeatedly to tamp the intimal layer and occlusion aside in the true lumen so blood flows through the previously occluded segment of artery. If the device fails to re-enter true lumen surgery is the “bail-out” procedure required immediately to place a bypass graft around the occlusion.
The prior art device of US Pub. No. 2008/0243065, which is in clinical trials as OffRoad® finds the true lumen from the false lumen by a different means than those used by Pioneer® and Outback®. It describes a conical balloon with inverted neck on distal end that is inflated in a dissection between artery layers (false lumen) located in healthy tissue distal to the occlusion. The balloon catheter is acutely bent in direction of true lumen by inflating the conical balloon which pushes its large distal end with inverted neck toward true lumen while the smaller proximal end of conical balloon remains close to false lumen. The conical balloon is thus in the false lumen with its inverted end pointing toward true lumen. In one configuration a guidewire in catheter lumen is used to pierce intimal layer and enter the true lumen while in another configuration a hollow needle is introduced through the balloon catheter to pierce the intimal layer. Since the catheter is pointed toward the true lumen it is also pointed at the artery wall opposite with no means of limiting the distance the piercing component will travel. But whether or not opposite wall is injured, the healthy tissue in which balloon is inflated is injured and collateral vessels attached in that healthy tissue may bleed and clot which would be sufficient to terminate the percutaneous procedure and bail out to surgery. The acute bending the catheter is also a weakness, making lumen smaller and creating other complications that are addressed by alternative configurations that place a joint at bend or make bend of an especially flexible material. An alternative configuration of this prior art device uses a longer cylindrical balloon with inverted neck to make the hollow needle more parallel to longitudinal axis but this causes balloon catheter to be more sharply bent and the length of healthy tissue injured is even longer thus gaining little while making the balloon catheter weaker and more prone to failure by an even more acute bend. This prior art focuses on re-entry, stating only that guidewire in balloon catheter makes the dissection between layers, i.e. the false lumen.
Another prior art device for re-entry of true lumen from false lumen is described in U.S. Pat. No. 8,241,311. The invention limits itself to re-entry even more than the inverted neck balloon device does as it suggests use of a laser wire or radiofrequency electrode to bore the false lumen without describing how these alternatives achieve those objects or claiming them. It also suggests use of radiopaque elements to find the true lumen but does not claim them. It does claim a lower profile than the prior art Pioneer® and Outback® devices. It avoids the need for bulky means, such as ultrasound by simply extending a cutting blade from the side of the re-entry guidewire and circumferentially rotating the blade 360 degrees. Since this includes all possible directions it includes the direction the true lumen is in. If the blade is not sufficiently extended to completely sever the intimal layer with this circumferential maneuver, the device provides a balloon for enlarging the 360 degree opening thus splitting the intimal layer. But no balloons is provided for tamping aside the occlusion, rather a stent is prescribed for opening the lumen to allow blood to flow.
There is also prior art for a mechanism that limits distance hollow needle advances to prevent it from piercing wall opposite. The need for this type of mechanism and other described means of finding true lumen are eliminated with present device.
The present invention provides a means of steering a J-tip guidewire with a piercing stylet wire transluminally (through true lumen) to the puncture site where the stylet wire pierces the intimal layer, provides an axis of rotation for screw grooves that assist the entry of J-tip guidewire through intimal layer, stiffens J-tip enough to make it form the correct size loop that dissects a false lumen between layers of the artery wall and before entering healthy tissue inflates one or more balloons in false lumen to make longitudinal exes of false and true lumen approximately coincident or parallel. Thus stylet wire points straight ahead to pierce intimal layer rather than pointing dangerously at opposite wall. A plurality of balloons is used rather than only one balloon to quickly tamp aside the entire length of occlusion, wrapped in diseased section of intimal layer without injury to adjacent healthy tissue or pointing piercing instrument dangerously at opposite artery wall. Since this device does not use ultrasound or orthogonal X-ray fluoroscopy to “find” true lumen but uses one or more balloons to simply push false lumen into true lumen it is difficult to see how this device will fail to “find” the true lumen in some percentage of cases or. In addition, the profile of present device may be made small enough to be used in coronary arteries and those arteries below-the-knee, e.g. 1-2 mm. Further, the steering guidewire revealed for assisting operator in transluminally approaching hard-to-reach puncture sites may be of use as a substitute for various shaped guide catheters, e.g. Judkins, Amplatz, used to locate and enter the ostium of coronary arteries where they branch from the aorta.
The present invention avoids the disadvantages of prior art while providing advantages as described, in summary providing the following unique advantages over prior art:    1. Provides means of steering guidewire and stylet wire to puncture site which is point of entry into artery wall where occlusion abuts wall and makes entry difficult from certain angles;    2. Stylet wire that provides piercing means to aid entry of J-tip guidewire through intimal (innermost) layer of artery wall and also provides axis of rotation for J-tip guidewire and other elongated instruments that may have screw grooves or vanes for screwing through innermost layer of artery wall;    3. Stylet wire provides stiffening for J-tip guidewire to maintain loop in tip that is of correct size to dissect a false lumen between intimal and medial layers of artery wall;    4. Advancing catheter provides alternative means of stiffening guidewire to maintain correct size loop and may have screw grooves or vanes on its end for screwing through innermost layer of artery wall;    5. Multiple concentric guidewires of increasing diameter may be used to steer or to enlarge false lumen and relieve pressure on J-tip guidewire as is often encountered with long occlusions;    6. A tamping catheter with one fluid line for distal balloon located on distal end of tamping catheter and another fluid line for the plurality of short tamping balloons located proximal to distal balloon as short balloons provide more even force than does long balloons and thus are more efficient and less time consuming;    7. Tamping catheter may also be advanced to slightly increase size of false lumen and thus relieve pressure on guidewire loop in long occlusions;    8. Distal tamping balloon provides means of tamping from false lumen into true lumen in unhealthy tissue thus not injuring healthy tissue whereas prior art balloon expands in healthy tissue;    9. Distal tamping to enter true lumen from false lumen avoids the need for complex and expensive ultrasound or orthogonal X-Ray imaging used by prior art devices to find true lumen from false lumen,    10. Use of stylet wire in J-tip guidewire allows present device to be of smaller diameter than prior art devices and thus usable in coronary arteries and below-the-knee arteries where prior art large diameter devices cannot be used;    11. Using tamping balloons to find true lumen from false lumen by pushing against adventitial layer to push aside intimal layer and occlusion aligns stylet wire with longitudinal axis of true lumen thus stylet wire is not pointed at an angle that places opposite wall in danger of being pierced as do all prior art devices. This also avoids the need for a mechanism to limit distance piercing element travels as provided by one prior art device;    12. The profile of present device is smaller than that of prior art devices by an amount that allows its use in below-the-knee applications and in many coronary applications, none of which can be treated with the relatively large diameter prior art devices discussed above.    13. Present device avoids the need of prior art device to circumferentially rotate a cutting blade 360 degrees which must include cutting intimal layer between false lumen and true lumen while providing the low profile of this prior art device.
Accordingly, there is no prior art with the object or means of accomplishing the objects as effectively, safely, and with less injury, danger and in less time as with the device revealed here.
Atherosclerosis is a disease that afflicts about 20 million people in the United States, more than any other life threatening disease. The Greek word “athero” means “gruel” and “sclerosis” “hardening,” so the disease is also known as “hardening of the arteries.” Today this gruel or atheroma is often called “plaque,” a deposit of cells, calcium, debris, and cholesterol in artery walls or in walls of conduits used as arteries. The occlusion narrows the artery lumen and the outermost or adventitial layer of the artery, which has about 80% of the strength of the wall, expands to compensate, but the net effect is that the lumen narrows. The plaque may rupture, cause blood clots, and/or calcify. The most extreme case is a chronic total occlusion (CTO of more than 99% occlusion for 3 months). An occlusion that narrows the artery to the point where it is incapable of delivering oxygen-carrying blood to muscles and organs beyond the occlusion requires intervention, surgical or percutaneous. There may or may not be symptoms or results from stress tests or EKG to indicate the need for intervention and a CTO is (presently) an indication for immediate surgical intervention. The arteries may be those of the heart or peripheral to the heart (usually legs). When the brain or heart is oxygen-deprived, death or impairment occurs rapidly. When muscles of the lower body are oxygen-deprived, death is slower but half die within 10 years. There may or may not be pain symptoms in the legs and gangrene may be the first clear indication with amputation or surgical intervention required to avoid death. Atherosclerosis may be treated by diet and drugs but patients often do not follow diets and the effects of tobacco smoke are irreversible even if the person stops smoking. So intervention is necessary in about 2 million cases in the US each year. About 75% of interventions are by percutaneous means rather than by surgical means as risk and debilitation are less. The gold standard treatment is a bypass graft placed by open surgery with its ends “grafted” to slits in the artery on each side of the occlusion thus carrying blood around it. The reason this is the gold standard is that a bypass graft remains functional about 7% years on average until 50% of cases fail. This is much longer than the duration of percutaneous means but despite this advantage, bypass grafts require surgery that is risky and debilitating. A coronary artery bypass graft (CABG) starts with a sternotomy which splits the sternum and pulls apart the rib cage and usually continues with a heart lung machine for oxygenating and circulating blood through the body for about an hour while the heart is intentionally stopped. After a CABG procedure a patient is in intensive care for a day or more, in hospital for a week and has a long recovery at home. This is done to allow the surgeon's hands to get to the non-beating heart to place about 8 sutures on each end of each bypass graft (sometimes more than 3 grafts-as in a triple bypass procedure) and the rate at which a skilled surgeon can do this is about a minute per suture. A heart lung machine can be safely used for about an hour and a triple bypass would require 48 sutures or more. There are so-called “da Vinci” machines that can assist the surgeon's fingers to remain steady enough to place coronary bypasses through openings in the chest while the heart continues to beat, but this machine is expensive and applicable in a limited number of cases. Open surgery to place a bypass graft in the lower body is not as debilitating but is risky and involves a long recovery time in comparison to percutaneous entry through a skin puncture, which allows most patients to go home the next day with almost immediate recovery. The most common catheter-based method of intervention is to enter the body through a skin puncture in the groin where the femoral artery is close to the skin. After percutaneous entry with a hollow needle piercing both skin and artery, a guidewire is advanced through the needle and through the vasculature and then it enters the narrow occlusion rather than going around it. A balloon on a catheter is then advanced over the guidewire and into the occlusion where it is inflated to push aside the occlusion and thus open the artery. But the occlusion starts to close (re-stenose) when the balloon is removed. Balloons used alone result in the occlusion remaining open about 2½ years on average until 50% of cases close again, i.e., fail. To keep the occlusion propped open, stents were developed in the 1990s. Stents are wire mesh tubes that increase the length of time balloon treatments last in coronary artery applications to about 5 years until 50% fail. But in the longer arteries and occlusions of the legs, stents are likely to fracture so tend not to be used thus balloons are used alone.
The bypass graft for coronary arteries, which are generally less than 5 mm diameter, must be a vein, usually harvested from the patient's leg. It lasts about 7½ years on average until 50% of the bypass grafts need replacement. An artery of the leg is generally larger than 5 mm so the bypass graft around an occlusion in a leg artery can be made of artificial material. Blood flow in an artificial artery of 4 mm or less is too small for them to be of practical use. But flow is sufficient in some types of artificial graft tubes that minimize resistance and are of 5 mm or greater diameter so that they last almost 7½ years on average, i.e. until 50% of patients have experienced failed grafts. Therefore artificial bypass grafts are preferred in legs, but surgery is required to place them. Percutaneous treatments have largely replaced surgical bypass graft treatments but have not achieved the long duration of the bypass graft placed surgically. Therefore there is a continuing search for inventions that increase the duration of percutaneous treatments including those for placing a bypass graft percutaneously. This is in hope that a treatment means will be found that lasts 7½ years rather than the 2½ years for balloon angioplasty alone or for 5 years when a stent can be used. But so far no treatment means has been found that extends duration to greater than 2½ years except the stent that creates such a problem of fracturing that it is not used in long occlusions of the leg arteries. There is also the problem of the occlusion growing back through the open mesh in stents. This was partially dealt with in 2005 by placing a substance on the stent that eluted over time to resist that growth. But that drug has created other problems, like causing blood clots that sometimes get caught in an artery of the brain causing a stroke. Eluting stents are used as are bare stents, but generally only in short coronary applications. The fact that stents tend to fracture in the legs has given rise to alternatives called stent grafts and to complete removal of the occlusion rather than pushing it aside. Contrary to expectations, complete removal, by any of several methods, including scraping with a blade, laser, freezing, and a roto-rooter device, results in re-growth of the occlusion in a shorter time than by pushing it aside with a balloon. However, after such plaque removal, a stent graft may be placed with the intention of keeping the occlusion from growing back. Stent grafts are generally successful in preventing the occlusion from growing back through the graft tube but the occlusion tends to grow back around the ends generally requiring repeat treatment in 50% of cases in less than 2½ years, and thus providing no improvement over a balloon alone without using the stent graft. These stent grafts have included ePTFE and heparin bioactive surfaces to inhibit intimal hyperplasia and re-growth of the occlusion. But the re-growth around the ends makes the duration for stent grafts no longer or even shorter than the duration for balloons alone. Balloon treatments have largely replaced surgical bypass graft treatments but they have not achieved the long duration of the bypass graft placed surgically. Each year in the US there are about 310,000 coronary artery bypass grafts (CABG) and 178,000 bypass grafts in legs placed surgically while there are more than 1.7 million percutaneous interventions.
It may be recognized that a successful combination of the effectiveness of bypass graft duration and the safety of percutaneous delivery would replace currently used means that have only one, not both. Prior art by the present inventor and by other inventors has described devices for combining means of placing a bypass graft around occlusions in coronary arteries outside the artery wall as is done in CABG surgery with percutaneous entry. None of these devices has been proven by clinical trials that resulted in approval by the Food and Drug Agency (FDA) for use. This is not because the bypass graft did not provide the longer duration but generally because of the problem of graft failure or real or assumed problems one or more steps in the percutaneous process of placing the graft. For instance, doubts have often been expressed about whether these prior art devices can accomplish re-entry into the artery after creating a passageway outside the artery wall. There is no such doubt about another means of re-entry after bypassing the occlusion between layers of the artery wall rather going outside the artery wall. That process, subintimal angioplasty, was originally developed in 1988 for treating CTOs in which the occlusion has no opening that can be entered with a balloon. It was originally accomplished with a collection of commonly available general purpose devices. The procedure was not extensively used, possibly because it requires substantial skill to use the collection of devices and it is counterintuitive to intentionally dissect two layers of an artery wall. But specialized devices are now available to make the process easier and to increase the number of cases that can be successfully treated. Prior art percutaneous devices are able to exit the artery lumen at the point of an occlusion, force a guidewire loop between intimal and medial layers of artery wall and re-enter the artery lumen after creating a passageway or false lumen between those layers that passes around the occlusion. That is, the true lumen is re-entered from the false lumen, and this is accomplished in about 80% of cases where it is attempted. At least two such devices have been approved by the FDA and are in use today; another simpler device is in clinical trials. The invention revealed here is of this type with improvements and means of avoiding recognized problems with prior art devices as have been described and summarized previously.
The product of subintimal angioplasty is a segment of previously occluded artery in which the occlusion has been pushed aside wrapped in the intimal lining from the diseased section of artery. This product is similar to complete removal of the occlusion by means of freezing, lasering, scraping or existing devices and to pushing aside the occlusion by a balloon that can be used in cases that are not CTO. Aside from the fact that the subintimal (SI) procedure is the only way to treat the ⅓rd of cases that are CTOs, it can be used for non-CTO cases. SI can be performed in less time than can complete removal and would be used in non-CTO cases if there were a means of treatment that used the product of SI to increase the duration of treatment to longer than 2½ years. The 2½ years would be comparable to but not superior to use of balloons alone in non-CTO cases. Therefore this would not be an advantage for non-CTO cases, but if the subintimal procedure can be combined with a graft tube that lasts as long as the 7½ years achieved by bypass grafts or even 5 years as achieved with stents (which tend to fracture in legs), or even somewhat longer than 2½ years it would benefit a large number of people. Since SI provides a segment of artery previously occluded there is currently a search for the kind of graft that will extend the duration. This search is relevant to the present invention but not part of the invention. Briefly, it may be noted that stent grafts, though successfully used for cases involving aneurysms, have not accomplished an improvement over the balloon alone in cases where there is an occlusion. Contouring stent graft ends has not solved the problem of occlusions growing back around the stent graft ends. Efforts also have been made to stabilize the connection at each end so there is no rubbing of graft ends and artery wall during pulsing, but no solution has been found. The present inventor is submitting a patent application for such a bypass graft but the present patent application reveals an improved means of producing the subintimal arteriotomy needed to place such a graft tube.